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          <th colspan="3" align="center">Removing Log Files</th>
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            <h2 class="title" style="clear: both"><a id="logfileremoval"></a>Removing Log Files</h2>
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      <p>
            By default DB does not delete log files for you. For this reason,
            DB's log files will eventually grow to consume an
            unnecessarily large amount of disk space. To guard against
            this, you should periodically take administrative action to
            remove log files that are no longer in use by your application.
        </p>
      <p>
            You can remove a log file if all of the following are true:
        </p>
      <div class="itemizedlist">
        <ul type="disc">
          <li>
            <p>
                    the log file is not involved in an active transaction.
                </p>
          </li>
          <li>
            <p>
                    a checkpoint has been performed
                    <span class="emphasis"><em>after</em></span> the log file was
                    created.
                </p>
          </li>
          <li>
            <p>
                    the log file is not the only log file in the
                    environment.
                </p>
          </li>
          <li>
            <p>
                    the log file that you want to remove has already been
                    included in an offline or hot backup.
                    Failure to observe this last condition can cause your 
                    backups to be unusable.
                </p>
          </li>
        </ul>
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      <p>
            DB provides several mechanisms to remove log files that
            meet all but the last criteria (DB has no way to know which
            log files have already been included in a backup). The
            following mechanisms make it easy to remove unneeded log files,
            but can result in an unusable backup if the log files are not first 
            saved to your archive location. All of the following
            mechanisms automatically delete unneeded log files for you:
        </p>
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          <li>
            <p>
                    Run the <span class="command"><strong>db_archive</strong></span> command line
                    utility with the <code class="literal">-d</code> option. 
                </p>
          </li>
          <li>
            <p>
                    From within your application, call the
                        <span>
                            <code class="methodname">DB_ENV-&gt;log_archive()</code>
                            
                            method with the <code class="literal">DB_ARCH_REMOVE</code> flag.
                        </span>
                        
                </p>
          </li>
          <li>
            <p>
                      <span>
                            Call
                        <span>
                            <code class="methodname">DB_ENV-&gt;log_set_config()</code>
                            
                            method with the <code class="literal">DB_LOG_AUTO_REMOVE</code> flag.
                        </span>
                        
                            Note that this flag can be set at any point in
                            the lifetime of your application. Setting this
                            parameter affects all environment handles
                            opened against the environment; not just the
                            handle used to set the flag.
                      </span>
                        
                </p>
            <p>
                    Note that unlike the other log removal mechanisms
                    identified here, this method actually causes log files
                    to be removed on an on-going basis as they become
                    unnecessary. This is extremely desirable behavior if
                    what you want is to use the absolute minimum amount of
                    disk space possible for your application. This
                    mechanism <span class="emphasis"><em>will</em></span> leave you with
                    the log files that are required to run normal recovery.
                    However, it is highly likely that this mechanism will
                    prevent you from running catastrophic recovery.
                </p>
            <p>
                    Do NOT use this mechanism if you want to be able to
                    perform catastrophic recovery, or if you want to be
                    able to maintain a hot backup.
                </p>
          </li>
        </ul>
      </div>
      <p>
            In order to safely remove log files and still be able to
            perform catastrophic recovery, use the
            <span class="command"><strong>db_archive</strong></span> command line utility as follows:
        </p>
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        <ol type="1">
          <li>
            <p>
                    Run either a normal or hot backup as described in
                    <a class="xref" href="backuprestore.html" title="Backup Procedures">Backup Procedures</a>. Make
                    sure that all of this data is safely stored to your
                    backup media before continuing.
                </p>
          </li>
          <li>
            <p>
                    If you have not already done so, perform a checkpoint.
                    See <a class="xref" href="filemanagement.html#checkpoints" title="Checkpoints">Checkpoints</a>
                    for more information.
                </p>
          </li>
          <li>
            <p>
                    If you are maintaining a hot backup, perform the hot
                    backup procedure as described in
                    <a class="xref" href="hotfailover.html" title="Using Hot Failovers">Using Hot Failovers</a>.
                </p>
          </li>
          <li>
            <p>
                    Run the <span class="command"><strong>db_archive</strong></span> command line
                    utility with the <code class="literal">-d</code> option against
                    your production environment. 
                </p>
          </li>
          <li>
            <p>
                    Run the <span class="command"><strong>db_archive</strong></span> command line
                    utility with the <code class="literal">-d</code> option against
                    your failover environment, if you are maintaining one.
                </p>
          </li>
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